View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by College of William & Mary: W&M Publish W&M ScholarWorks VIMS Articles Virginia Institute of Marine Science 2009 The Repulsive And Feeding-Deterrent Effects Of Electropositive Metals On Juvenile Sandbar Sharks (Carcharhinus Plumbeus) Richard Brill Virginia Institute of Marine Science, [email protected] Peter Bushnell Leonie Smith Coley Speaks Rumya Sundaram See next page for additional authors Follow this and additional works at: https://scholarworks.wm.edu/vimsarticles Part of the Aquaculture and Fisheries Commons Recommended Citation Brill, Richard; Bushnell, Peter; Smith, Leonie; Speaks, Coley; Sundaram, Rumya; and Wang, John, "The Repulsive And Feeding-Deterrent Effects Of Electropositive Metals On Juvenile Sandbar Sharks (Carcharhinus Plumbeus)" (2009). VIMS Articles. 555. https://scholarworks.wm.edu/vimsarticles/555 This Article is brought to you for free and open access by the Virginia Institute of Marine Science at W&M ScholarWorks. It has been accepted for inclusion in VIMS Articles by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. Authors Richard Brill, Peter Bushnell, Leonie Smith, Coley Speaks, Rumya Sundaram, and John Wang This article is available at W&M ScholarWorks: https://scholarworks.wm.edu/vimsarticles/555 298 Abstract—Reducing shark bycatch The repulsive and feeding-deterrent effects and depredation (i.e., damage caused by sharks to gear, bait, and desired of electropositive metals on fish species) in pelagic longline fisher- ies targeting tunas and swordfish is juvenile sandbar sharks a priority. Electropositive metals (i.e., (Carcharhinus plumbeus) a mixture of the lanthanide elements lanthanum, cerium, neodymium, and praseodymium) have been shown to Richard Brill (contact author)1 deter spiny dogfish (Squalus acanth- Peter Bushnell2 Rumya Sundaram2 ias, primarily a coastal species) from 3 5 attacking bait, presumably because of Leonie Smith Eric Stroud interactions with the electroreceptive Coley Speaks4 John Wang6 system of this shark. We undertook to determine the possible effectiveness of electropositive metals for reducing Email address for contact author: [email protected] the interactions of pelagic sharks with 1 Cooperative Marine Education 3 Department of Biological Science longline gear, using sandbar sharks and Research Program Bangor University (Carcharhinus plumbeus, family Northeast Fisheries Science Center Bangor Gwynedd, LL57 2DG, UK Carcharhinidae) as a model species. National Marine Fisheries Service, NOAA 4 Department of Marine Science The presence of electropositive metal 166 Water Street Hampton University deterred feeding in groups of juvenile Woods Hole, Massachusetts, 02543 Hampton, Virginia, 23668 sandbar sharks and altered the swim- Present address: Virginia Institute 5 Shark Defense Technologies, LLC ming patterns of individuals in the of Marine Science P.O. Box 2593 absence of food motivation (these indi- PO Box 1346 (mail) Oak Ridge, New Jersey 07438 viduals generally avoided approaching Route 1208 Greate Rd. 6 Joint Institute for Marine and Atmospheric electropositive metal closer than ~100 Gloucester Point, Research University of Hawai’i at Manoa cm). The former effect was relatively Virginia 23062 short-lived however; primarily (we 1000 Pope Road 2 Department of Biological Sciences assume) because competition with Honolulu, Hawaii, 96822 Indiana University South Bend other individuals increased feeding 1700 Mishawaka Avenue motivation. In field trials with bottom South Bend, Indiana, 46634 longline gear, electropositive metal placed within ~10 cm of the hooks reduced the catch of sandbar sharks by approximately two thirds, com- pared to the catch on hooks in the proximity of plastic pieces of similar The worldwide bycatch of sharks is and Myers, 2004; Gilman et al., 2008), dimensions. Electropositive metals estimated to be 260,000–300,000 and these species are now included therefore appear to have the poten- tial to reduce shark interactions in metric tons annually (11.6 to 12.7 on the International Union for Con- pelagic longline fisheries, although million individual sharks) (Bonfil, servation of Nature (IUCN) Red List the optimal mass, shape, composition, 1994; Camhi et al., 1998). In pelagic of Threatened Species (IUCN, 2008). and distance to baited hooks remain longline fisheries targeting tunas Such severe reductions in elasmo- to be determined. and swordfish, it is not uncommon branch populations have the poten- for the number of sharks caught to tial to detrimentally restructure exceed that of the desired fish species marine ecosystems (Jackson et al., (Stevens, 1992; Bonfil, 1994; Gilman 2001; Myers and Worm, 2003; Worm et al., 2008). Shark populations are et al., 2006; Myers et al., 2007). Sur- especially vulnerable to high rates vival rates of pelagic sharks released of fishing mortality because of their from longline gear appear high for slow growth rates, low reproductive animals that are not moribund when output, and late sexual maturity. the gear is retrieved (Moyes et al., Once depleted, they also generally 2006). Nonetheless, reduction of both have slow rates of recovery because shark bycatch and depredation (i.e., of these characteristics (Smith and shark damage to longline gear, bait, Snow, 1998; Chen and Yuan, 2006). and desired fish species) is considered Manuscript submitted 31 October 2008. Manuscript accepted 2 March 2009. Scalloped hammerhead (Sphyrna a priority (Gilman et al., 2008, Man- Fish. Bull. 107:298–307 (2009). lewini), oceanic whitetip (Carcha- delman et al., 2008). rhinus longimanus), and tiger shark Sharks (but not the large pelagic The views and opinions expressed (Galeocerdo cuvier) populations have teleosts targeted by longline fisher- or implied in this article are those of the author and do not necessarily already decreased within the range ies) possess a unique sensory system reflect the position of the National from 60% to 99% of their historical based on the ampullae of Lorenzini Marine Fisheries Service, NOAA. biomass (Baum et al., 2003; Baum that can detect electric field gradi- Brill et al.: The repulsive and feeding-deterrent effects of electropositive metals on Carcharhinus plumbeus 299 ents as small as 5 nV/cm (Haine et al., 2001). These Our experiments with captive sandbar sharks include ampullary receptors are most sensitive to frequencies tests of the ability of electropositive metals to influence from 1 to 8 Hz (Montgomery, 1988), are capable of the swimming patterns of individual animals in the detecting weak electric fields generated by neuromus- absence of food motivation and to repel sharks from cular activity, and can guide sharks to prey in the pieces of cut bait. The former is intended to quantify absence of other sensory stimuli (Kajiura and Holland, repulsive distances, and both are intended to provide 2002; Kajiura, 2003; Collin and Whitehead, 2004). data directly comparable with those obtained previously It should be possible, therefore, to develop effective with spiny dogfish sharks (Stoner and Kaimmer, 2008; deterrent procedures that could take advantage of the Tallack and Mandelman, in press). Our deployment of sharks’ electroreceptive sense. The procedures could longline fishing gear in a tidal lagoon system used as then decrease the bycatch and incidental mortality a nursery area by juvenile sandbar sharks (Conrath, of sharks and increase fishing efficiency and yield of 2005; Conrath and Musick, 2007) tested the ability of the desired fish species. Strong electric fields have electropositive metal to deter sharks under field condi- been shown to deter approaching sharks, presumably tions and provided data comparable to data from recent by overloading their electrosensory modality (Smith, studies where spiny dogfish sharks were targeted by a 1974, 1991; Cliff and Dudley, 1992). However, cur- similar method (Kaimmer and Stoner, 2008; Tallack rently available electronic devices for achieving this and Mandelman, in press). behavioral response are designed to protect humans and aquaculture structures from shark attack and are large, expensive, and not practical for deployment on Materials and methods longline fishing gear. There are no data on the mini- mum field strength needed to achieve electrosensory Experiments with captive animals were conducted repulsion. during the summer months (June through August 2007) Electropositive metals (generally mixtures of the lan- at the Virginia Institute of Marine Science, Eastern thanide elements praseodymium, neodymium, cerium, Shore Laboratory, in Wachapreague, Virginia. Juvenile lanthanum, samarium, and yttrium) rouse juvenile sandbar sharks weighting up to ~5 kg (i.e., neonates to lemon sharks (Negaprion brevirostris), nurse sharks approximately 5 years old; Casey and Natanson, 1992) (Ginglymostoma cirratum), and spiny dogfish sharks were captured with standard recreational hook-and-line (Squalus acanthias) from tonic immobility when brought fishing gear in the surrounding tidal lagoon system and close to the head (Stoner and Kaimmer, 2008). Elec- transported to an outdoor circular fiberglass tank (7 m tropositive metals have also been shown to deter spiny diameter, 1.8 m deep) as described previously (Brill et. dogfish sharks from attacking baits in a tank study al., 2008). The tank was supplied with sea water pumped (Stoner and Kaimmer, 2008), and to reduce the catch of from the adjacent tidal lagoon which was passed through